The lump from injecting in the same spot is called lipohypertrophy (or possibly lipodystrophy) and it can actually affect absorption of the medication! You might have been getting inconsistent dosing because of it. The good news is it usually resolves if you avoid that area for a few months.
My injection rotation system:
- I divide my abdomen into 4 quadrants (upper left, upper right, lower left, lower right)
- I rotate through them each week: week 1 upper left, week 2 upper right, etc.
- Within each quadrant, I vary the exact spot by an inch or so
- I stay at least 2 inches away from my navel
This way I don't hit the same spot more than once a month.